The Algerian town of Ain Sefra — known as "the gateway to the desert" — is probably not the first place that springs to mind when someone mentions snow.

But on Monday the desert town was hit by a freak snowstorm — the first in the Sahara in almost 40 years. Snow could be seen not only on the tops of the surrounding Atlas Mountains, but also in the red dunes of the desert.

The Sahara is one of the hottest regions of the world, with temperatures that can soar to 47 degrees Celsius. The last significant snowfall to hit the region fell in 1979, when a 30-minute snowfall stopped traffic, and it has since seen dustings of snow in 2005 and 2012. Although the temperature in winter can dip below the freezing point, snow is rare because the area is one of the driest on earth.